Project Summary The objective of this project is to understand the role of extracellular vesicles in mediating the beneficial effects of bariatric surgery, the most effective treatment for obesity, and a potent therapeutic for type 2 diabetes and associated cardiovascular disease risk factors. The mechanisms by which bariatric surgery drives amelioration of these health conditions is currently unknown, despite misconceptions that mechanical restriction or nutrient malabsorption contribute. Instead, evidence points to some combination of endocrine, neural, and microbial influences. This diversity of organ systems involved in mediating the effects of bariatric surgery suggests a secreted regulator may be involved. Extracellular vesicles are one mechanism of intra-cellular and intra-organismal communication employed by most gut microbial and intestinal epithelial cells, and have been demonstrated to modulate mammalian glucose regulation, adaptive immunity, and intestinal physiology. Additionally, extracellular vesicles are currently under development as clinical targets and vehicles of drug delivery for a host of diseases. The proposed research focuses on the role of extracellular vesicles from the mucus membrane of the small intestinal epithelium, which preliminary data demonstrates are compositionally altered relative to sham controls in a mouse model of vertical sleeve gastrectomy (VSG), the most popular form of bariatric surgery in the United States. Here, the proposed research aims to further understand the effect of this compositional change in mucosal extracellular vesicles by evaluating the transcriptional landscape and modulations, cellular targets, and functional effects of post-VSG extracellular vesicles, through a series of in silico, in vitro, ex vivo, and in vivo studies. The results of these studies will provide novel clinically-relevant evidence for the role and potential mechanisms extracellular vesicles employ and their role in driving type 2 diabetes pathogenesis and remission. Further, this training plan will provide new insights into potential therapeutic avenues to improve bariatric surgery methods, prognostic indications, and/or preventative strategies for the treatment of obesity, type 2 diabetes, and associated gastrointestinal diseases. The Seeley laboratory is a world leader in the use and development of animal models of bariatric surgery to understand the etiology of obesity and type 2 diabetes, providing the ideal training environment in which to conduct the proposed research.